The field of the invention is treatment of eye disorders, and more particularly setons used to treat uncontrolled intraocular pressure.
Glaucoma is a disease of the eye which affects a substantial number of people. It involves uncontrolled intraocular pressure within the eye caused by obstruction of the trabecular meshwork and causes permanent damage to the optic nerve. Surgical treatment of glaucoma has been limited due to failure to control intraocular pressure as well as post-operative complications which tend to exacerbate the pre-operative increased intraocular pressure.
The eye is a complex organ. The front of the eye is covered by the cornea. The cornea refracts light through the anterior chamber to the lens. Muscles control the size of the entrance aperture of the eye, also known as the pupil. The lens is suspended by the iris and focuses the refracted light through the vitreous chamber and onto the retina in the back of the eye. The shape of the lens can be varied by muscles within the eye to focus on objects that are close or far away.
Normally, the fluid within the eye, known as aqueous humor is produced by the ciliary body and migrates through the pupil, into the anterior chamber, through the trabecular meshwork and into the aqueous veins which form fluid collection channels beneath the conjunctiva. Glaucoma results when the intraocular pressure is not relieved by aqueous migration. This is typically due to obstruction of the trabecular meshwork. The uncontrolled high pressure of glaucoma leads to permanent damage of the optic nerve.
Medical treatment of the uncontrolled high pressure of glaucoma has had varying success. Medicines in the form of eye drops or pills to reduce the production of aqueous in the ciliary body and/or increase the outflow of aqueous through the trabecular meshwork are often used. In some cases, surgical filtration procedures are attempted. One such technique creates a hole through the limbus and excises a piece of the trabecular meshwork. After filtration surgery, the aqueous will flow from the anterior chamber through the excised surgical area and into the space beneath the conjunctiva where it is finally absorbed by the body.
Another attempt to improve the filtration through the trabecular meshwork involves placing several Argon laser burns throughout the enter circumference of the trabecular meshwork in hopes of opening up the trabecular meshwork spaces. This procedure is called Argon laser trabeculoplasty.
In certain high risk cases, these surgical techniques are typically unsuccessful due to the post-operative scarring of the wound or the scleral tissue. This scarring prevents migration of the aqueous out of the eye and results in a recurrance of the uncontrolled intraocular pressure of glaucoma.
Another method to attempt to relieve the uncontrolled high pressure of glaucoma is to perform an iridencleisis. The procedure involves pulling a piece of the iris through a wound cut into the anterior chamber. Serious infection and inflammation of the wound often results from this procedure. In addition, a piece of cartilage has been implanted into the eye in an attempt to control glaucoma. This procedure failed due to scar tissue forming about the wound and the closure preventing migration of aqueous. Finally, seton implants in the form of polypropylene tubing and a Krupin Valve implant have failed due to post-operative extrusion of the implants through the wound as well as the formation of clots which act to inhibit the flow of aqueous.
In cases where medicines, laser trabeculoplasty and surgical filtration procedures, such as a trabeculectomy, have failed, the only medically proven method for controlling pressure within the eye is to permanently damage the ciliary body. This procedure, known as Cyclocrytherapy, involves externally freezing the sclera above the ciliary body. This process damages any potentially functioning trabecular meshwork and is frought with complications, such as bleeding within the eye and other significant damage to the eye, thereby causing loss of use of the eye.